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1. A Life Cycle Assessment Approach for Vegetables in Large-, Mid-, and Small-Scale Food Systems in the Midwest US

   https://doi.org/10.3390/su132011368  

   Stone, Tiffanie F.; Thompson, Janette R.; Rosentrater, Kurt A.; Nair, Ajay (October 2021, Sustainability)

   Although vegetables are important for healthy diets, there are concerns about the sustainability of food systems that provide them. For example, half of fresh-market vegetables sold in the United States (US) are produced in California, leading to negative impacts associated with transportation. In Iowa, the focus of this study, 90% of food is imported from outside the state. Previous life cycle assessment (LCA) studies indicate that food consumption patterns affect global warming potential (GWP), with animal products having more negative impacts than vegetables. However, studies focused on how GWP, energy, and water use vary between food systems and vegetable types are less common. The purpose of this study was to examine these environmental impacts to inform decisions to buy locally or grow vegetables in the Midwest. We used a life cycle approach to examine three food systems (large-, mid-, and small-scale) and 18 vegetables commonly grown in/near Des Moines, Iowa. We found differences in GWP, energy, and water use (p ≤ 0.001 for each) for the three food systems with the large-scale scenario producing more emissions. There were also differences among vegetables, with the highest GWP for romaine lettuce (1.92 CO2eq/kg vegetable) approximately three times that of leaf lettuce (0.65 CO2eq/kg vegetable) at the large scale. Hotspots and tradeoffs between GWP, energy, and water use were also identified and could inform vegetable production/consumption based on carbon and water use footprints for the US Midwest. 

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2. Sustainability of lettuce production: A comparison of local and centralized food production

   https://doi.org/10.1016/j.jclepro.2023.139224  

   Maynard, Reid; Burkhardt, Jesse; Quinn, Jason C (November 2023, Journal of Cleaner Production)

   Communities are considering local food production in response to the pressing need to reduce food system greenhouse gas (GHG) emissions. However, local food systems can vary considerably in design and operation, including controlled environment agriculture (CEA), which refers to agricultural production that takes place within an enclosed space where environmental conditions, such as temperature, humidity, and light, are precisely controlled. Such systems require a considerable amount of energy and thus emissions; therefore, this study seeks to quantify these environmental impacts to determine how local CEA systems compare to alternative systems. For this study’s methods, we apply life cycle assessment methodology to quantify the cradle-to-storeshelf GHG emissions and water consumption of four lettuce production systems: local indoor plant factory, local greenhouse, local seasonal soil, and conventional centralized production in California with transportation. Using geographically specific inputs, the study estimates the environmental impact of the different production systems including geospatially resolved growth modeling, emissions intensity, and transportation distances. The results include the major finding that baseline CEA systems always have higher GHG emissions (2.6–7.7 kg CO2e kg−1) than centralized production (0.3–1.0 kg CO2e kg−1), though water consumption is significantly less owing to hydroponic efficiency. In contrast, local seasonal soil production generally has a lower GHG impact than centralized production, though water consumption varies by crop yield and local precipitation during growing seasons. Scenario analyses indicate CEA facilities would need to electrify all systems and utilize low-carbon electricity sources to have equivalent or lower GHG impacts than California centralized production plus transportation. We conclude that these results can inform consumers and policy makers that local seasonal production and conventional supply chains are more sustainable than local CEA production in near-term food-energy-water sustainability nexus decision making. 

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3. Identifying opportunities for nature-based solutions with geospatialized life cycle assessments and fine-scale socioecological data

   https://doi.org/10.1088/1748-9326/ad959e  

   Shirkey, Gabriela; Anctil, Annick; John, Ranjeet; Kolluru, Venkatesh; Mungai, Leah; Kashongwe, Herve; Cooper, Lauren_T; Celik, Ilke; Fisher, Joshua_B; Chen, Jiquan (December 2024, Environmental Research Letters)

   Abstract As we increasingly understand the impact that land management intensification has on local and global climate, the call for nature-based solutions (NbS) in agroecosystems has expanded. Moreover, the pressing need to determine when and where NbS should be used raises challenges to socioecological data integration as we overcome spatiotemporal resolutions. Natural and working lands is an effort promoting NbS, particularly emissions reduction and carbon stock maintenance in forests. To overcome the spatiotemporal limitation, we integrated life cycle assessments (LCA), an ecological carbon stock model, and a land cover land use change model to synthesize rates of global warming potential (GWP) within a fine-scale geographic area (30 m). We scaled National Agricultural Statistic Survey land management data to National Land Cover Data cropland extents to assess GWP of cropland management over time and among management units (i.e. counties and production systems). We found that cropland extent alone was not indicative of GWP emissions; rather, rates of management intensity, such as energy and fertilizer use, are greater indicators of anthropogenic GWP. We found production processes for fuel and fertilizers contributed 51.93% of GWP, where 33.58% GWP was estimated from N₂O emissions after fertilization, and only 13.31% GWP was due to energy consumption by field equipment. This demonstrates that upstream processes in LCA should be considered in NbS with the relative contribution of fertilization to GWP. Additionally, while land cover change had minimal GWP effect, urbanization will replace croplands and forests where NbS are implemented. Fine-scale landscape variations are essential for NbS to identify, as they accumulate within regional and global estimates. As such, this study demonstrates the capability to harness both LCA and fine-resolution imagery for applications in spatiotemporal and socioecological research towards identifying and monitoring NbS. 

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4. Perceptions of high-tech controlled environment agriculture among local food consumers: using interviews to explore sense-making and connections to good food

   https://doi.org/10.1007/s10460-021-10261-7  

   Broad, G.M. (August 2021, Agriculture and human values)

   In recent years, new forms of high-tech controlled environment agriculture (CEA) have received increased attention and investment. These systems integrate a suite of technologies – including automation, LED lighting, vertical plant stacking, and hydroponic fertilization – to allow for greater control of temperature, humidity, carbon dioxide, oxygen, and light in an enclosed growing environment. Proponents insist that CEA can produce sustainable, nutritious, and tasty local food, particularly for the cities of the future. At the same time, a variety of critics raise concerns about its environmental impacts and energy use, high startup costs, and consumer accessibility challenges, among other issues. At this stage, however, relatively little research has explored actual consumer knowledge and attitudes related to CEA processes and products. Guided by theories of sense-making, this article draws from structured interviews with local food consumers in New York City to examine what people know and think about high-tech CEA. From there, it explores the extent to which CEA fits into consumer conceptualizations of what makes for “good food.” Key findings emphasize that significant gaps in public understanding of CEA remain, that CEA products’ success will depend on the ability of the industry to deliver on its environmental promises, and that concerns about “unnatural” aspects of CEA will need to be allayed. Given the price premium at which high-tech CEA products are currently sold, the industry’s expansion will depend in large part on its ability to convince value-oriented food consumers that the products meet the triple-bottom-line of economic, social, and environmental sustainability goals. 

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5. The Impact of CO2 Enrichment on Biomass, Carotenoids, Xanthophyll, and Mineral Content of Lettuce (Lactuca sativa L.)

   https://doi.org/10.3390/horticulturae8090820  

   Holley, Jake; Mattson, Neil; Ashenafi, Eyosias; Nyman, Marianne (September 2022, Horticulturae)

   Carbon dioxide (CO2) concentrations affect the growth rate of plants by increasing photosynthesis. Increasing CO2 in controlled environment agriculture (CEA) provides a means to boost yield or decrease daily light integral (DLI) requirements, potentially increasing profitability of growing operations. However, increases in carbon dioxide concentrations are often correlated with decreased nutritional content of crops. The objectives of this experiment were to quantify the effects of carbon dioxide on the growth, morphology, and nutritional content of two lettuce varieties, ‘Rex’ and ‘Rouxai’ under four CO2 concentrations. Applied CO2 treatments were 400, 800, 1200, and 1600 ppm in controlled environment chambers with identical DLI. Lettuce was germinated for eight days in a greenhouse, then transplanted into potting mix and placed in a growth chamber illuminated by fluorescent lights. After 21 days, lettuce was destructively harvested, and fresh weight and plant volume were measured. Anthocyanins, xanthophylls, chlorophyll, and mineral concentration were measured. The lettuce fresh and dry weight increased with increasing CO2 concentrations, with the greatest increases observed between 400 and 800 ppm, and diminishing increases as CO2 concentration further increased to 1200 and 1600 ppm. Violaxanthin was observed to decrease in ‘Rouxai’ with increasing CO2 concentration. Largely, no significant differences were observed in lutein, anthocyanins, and mineral content. Overall, increasing concentrations of carbon dioxide can significantly increase the yield for lettuce in controlled environments, while not significantly reducing many of the nutritional components. 

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